Rock drilling tool



Oct. 21, 1952 SHEPHERD 2,614,812

ROCK DRILLING TOOL Filed June 25, 1949 F] sssrwqramm i si gg no HIS ATTORNEY- Patented Oct. 21, 1952 UNITED STATES PATENT- OFFICE I 2,614,812 1 .ROCK DRILLING TOOL Benjamin F. Shepherd, Phillipsburg, N. 1., as-

signor to Ingersoll-Rand Company, New York, N. Y., a corporation of New Jersey Application June 25, 1949, Serial No. 101,360

.4. Claims. (01. 2s5-e4) This invention relates to rock drilling tools, and more particularly to tools of this type having cutting elements of superior metal embedded in and bonded to a body of a different grade and less costly metal.

One object of the present invention is to improve the construction of rock drilling tools in order to make them more durable and eificient.

Another object is to obviate the chances of the cutting element of the drilling tool from becoming interlockingly engaged withthe rock surface and, in consequence, be extracted from the body of the tool.

Other objects will be in part obyious and in part pointed out hereinafter.

In the drawings accompanying this specification and in which similar reference numerals refer to similar parts,

Figure 1 is a longitudinal side view of the rock drilling tool constructed in accordance with the practice of the invention,

Figure 2 is an end view of the tool,

Figure 3 is a transverse view taken through Figure 2 on the line 3-3,

Figure 4 is a view similar to Figure 3 showing a modified form of the invention, and

Figure 5 is a transverse view taken through Figure 4 on the line 55.

Referring more particularly to the drawings and at first to the form of the invention shown in Figures 1 to 3 inclusive, 20 designates a drilling tool comprising a body 2| which may be either the leading end of a drill rod or a member formed separately for attachment to a drill rod.

The body 2| is shown as being of frusto-conical shape having a passage 22 for conveying cleansing fluid to the surface being drilled. In the end of the body 2| are slots 23 that li at right-angles to each other and open at their ends into the periphery of the body. The portions of the slots lying on the opposite sides of their intersection contain inserts 24 having portions extending forwardly of the body 2| to provide cutting edges 25. The cutting edges are defined by converging inclined surfaces 26 that extend from the opposed sides of the inserts and coincide with similar surfaces 21 on the front end of the body serving to define grooves 28 between adjacent inserts for the escape of cuttings from the working surface. The body. 2| is, moreover, provided with longitudinally extending grooves 29 in its periphery to register with the grooves 28 for the passage of such cuttings from the drill hole.

A tubular member 30 seated in the end of the body at the intersection of the slots 23 servesas an abutment for the inserts 24 and prevents them from being driven endwise of the slots 23 whenever their outer ends strike against the surface of the hole being drilled. The tubular member 30 and the inserts 24 are secured fixedly to the body by brazed joints 3| that preferably'extend along all theopposed surfaces of the, body and the parts inserted therein.

The inserts 24 are constructed of a harder metal, tungstencarbide for example, than the body 2|. They, thereforeyhave greater resistance to the abrasive action of the material being drilled and, consequently,.the peripheral surface of the body wears away at a faster rate than do the inserts. Thus, in time, the outer end portions of the inserts become uncovered and will extend beyond the surface of the body 2 l. 'Under these conditions, when the drilling tool rebounds from the working surface, the rearward surfaces or shoulders of the exposed ends of the inserts will strike against irregularities on the surface of the drill hole and cause the brazed joints to fail so that an insert is free to fallout of the body 2|. In many instances the damage thus caused is not detected until the drilling tool has become impaired to such an extent that it is no longer possible to recondition it.

With a view toward obviating an occurrence of the nature above described, it is contemplated herein to obviate the possibility of the outer ends of the inserts from coming into engagement with the surface of the drill hole in a manner that might result in damage to the brazed joints 3|. To this end the outer end surfaces 32 of the portions of the inserts lying in the slots 23 are each provided with a cavity 33 to minimize their areas in such degree that they will wear away at approximately the same rate as the comparatively large peripheral areas of the body 2| lying adjacent thereto. The cavities 33 may be of any desired shape and depth, those shown, by way of example, being of a length closely approximating the depth of the slots 23 and increasing in width toward the rearward surfaces of the inserts.

In order to prevent the lodgment of rock particles in the cavities 33 and which might become jammed between the end of the insert and the wall of the drill hole and force an insert out of the body, the cavities 33 are filled with a metallic material 34. Such material is preferably of the type used for bonding the inserts and the abutment member 30 to the body and is, therefore, sufliciently soft to wear away at at least the same rate as the body.

The form of the invention shown in Figures 4 and 5 differs from that previously described only in that the entire area of the end surfaces 35 of the portion of the inserts is relieved to cause said surfaces to lie entirely inside of the plane of the periphery of the adjacent portion of the body 2 I. This is accomplished by inclining the surface 35 from the juncture of the rearward ends of the inclined surfaces 26 with the main body of the inserts toward the axis of the body 2 l.

Preferably, the space existing 'between the sur face 35 and the periphery of the body 2| is also filled with brazing metal to exclude cuttings from the outer ends of the slots 23 I claim:

1. A rock drilling tool, comprising a bodyh-aving a slot in an end thereof opening into the periphery of the body, an insert in the slot having a cutting portion forwardly of the body extending to the periphery of the body, said insert having at least a portion of its outer end surface lying within-the slot, and a metallic filler within the slot to overlie such portion of the end surface of the insert.

2. A rock drilling tool, comprising a body having a slot in an end thereof opening into the periphery of the body, an-insert in the slot having a cutting portion forwardly of the body extending to the periphery of the'body, said insert having an end surface lying partly in the plane of the periphery of the vbody and partly within the slot, and a metallic filler in the slot to overlie the portion-of such end surface that lies within the-slot:

3. A rock drilling tool, comprising a body having a slot in an end thereof opening into the periphery of the body, an insert in the slot having a cutting portion forwardly of the body extending to the periphery of the body, and there being a cavity in the end surface of the insert adjacent the periphery of the body to minimize the area of the surface of the insert lying in the plane of the periphery of the body, and a metallic filler in the cavity.

4. A rock drilling tool, comprising a body having a slot in an end thereof opening into the periphery of the body, an insert in the slot having a cutting portion forwardly of the body extendin to the periphery of the body, an end surface on the portion of the insert rearwardly of the cutting portion inclined from the outer end of the cutting portion toward the axis of the body and lying within the slot, and a metallic filler in the slot between the inclined end surface of the insert and the end of the slot.

' BENJAMIN F. SHEPHERD.

REFERENCES CITED The following references are of record in the file of this patent: 1

UNITED STATES PATENTS 0 Curtis Mar. 28, 1950 

